1. Field of the Invention
The present invention relates to the generation of electrical power by means of hydroelectric conversion devices driven by the flow of ocean currents, and how to present such devices to said current. More specifically, the invention is intended for underwater deployment in the ocean, suspended between the ocean floor and surface by tethered and buoyant means, thereby bringing its power conversion devices into interaction with ocean currents at a selected depth, and in a manner particularly suited to periodic surfacing for maintenance and retrofit. The invention is remotely operated and monitored, flexibly configurable, potentially large in scale, and equipped with redundant means of communication and control, thus providing a composite “power plant” that is practical for the requirements of current-driven energy-conversion devices emplaced in the subsea water column.
In a time when alternative sources of power generation are in clear demand, practical solutions for ongoing and reliable operation in harsh undersea environments have obvious application. Though numerous inventions in this field have been proposed over the last century, the comparative practical benefits of the present invention (when comparable power output and maintenance requirements are considered) include minimal invasiveness to surface traffic or fishing; non-disruption of surface aesthetics; protection of primary equipment from the more violent and unpredictable surface currents and turbulence; ability to defend against more violent aquatic events by means of change in attitude or depth or by recall of the entire platform; and, most importantly, the ability to readily access the equipment in order to keep it functional and up-to-date. Furthermore, the present invention comprises a true system, embracing within its boundaries such practical and critical factors as mechanical deployment, station-keeping and retrieval, cable management, conveyance of power to shore, and a redundancy of communications means.
2. Description of Related Art
The proposition of harnessing ocean currents for the purposes of electrical power generation has a long history, beginning with surface currents being engaged by paddlewheel-type devices (either horizontal or vertical) or other means. Such U.S. Pat. No. 328,447 (Brady, 1885); U.S. Pat. No. 365,133 (Kessler, 1887); U.S. Pat. No. 408,075 (Brown, 1889); U.S. Pat. No. 833,361 (Wilmore, 1906); U.S. Pat. No. 867,192 (Dawson, 1907); U.S. Pat. No. 950,676 (Price, 1910); U.S. Pat. No. 958,467 (Bennett, 1910); U.S. Pat. No. 969,794 (Miner, 1910); U.S. Pat. No. 974,221 (Wilber, 1910); U.S. Pat. No. 1,109,839 (Henry, 1914); U.S. Pat. No. 2,379,324 (Topalov, 1945); U.S. Pat. No. 3,807,890 (Wright, 1974); U.S. Pat. No. 3,928,771 (Straumsnes, 1975); U.S. Pat. No. 3,973,864 (Atherton, 1976); U.S. Pat. No. 3,978,345 (Bailey, 1976); U.S. Pat. No. 4,023,041 (Chappell, 1976); U.S. Pat. No. 4,038,821 (Black, 1977); U.S. Pat. No. 4,160,624 (Smith, 1979); U.S. Pat. No. 4,224,793 (Gutsfeld, 1980); U.S. Pat. No. 4,301,377 (Rydz, 1981); U.S. Pat. No. 4,313,059 (Howard, 1982); U.S. Pat. No. 4,467,218 (Andruszkiw et al.,1984); U.S. Pat. No. 4,516,033 (Olson, 1985); U.S. Pat. No. 4,818,888 (Lenoir, III, 1989); U.S. Pat. No. 4,843,249 (Bussiere, 1989); U.S. Pat. No. 5,281,856 (Kenderi, 1994); U.S. Pat. No. 5,471,098 (Asay, 1995); U.S. Pat. No. 5,834,853 (Ruiz et al., 1998); U.S. Pat. No. 6,551,053 (Schuetz, 2003); U.S. Pat. No. 6,734,576 (Pacheco, 2004); U.S. Pat. No. 6,759,757 (Campbell, 2004); and U.S. Pat. No. 6,856,036 (Belinsky, 2005). Such inventions are indicative of the longstanding quest for conversion of kinetic energy in the ocean current into electrical energy. The same could be demonstrated for devices energized by the oscillatory nature of surface wave action; but as the present invention relates to subsurface current-based energy conversion, such need not be invoked herein.
Other surface (or near-surface) inventions have been patented involving specifically turbine (as opposed to, e.g., paddlewheel means) inventions for power generation: U.S. Pat. No. 1,147,658 (Stokes, 1915); U.S. Pat. No. 1,396,609 (Weisenborn, 1921); U.S. Pat. No. 3,986,787 (Mouton, Jr. et al., 1976); U.S. Pat. No. 4,095,918 (Mouton et al., 1978); U.S. Pat. No. 4,590,386 (Wiggs, 1986); U.S. Pat. No. 4,722,665 (Tyson, 1988); U.S. Pat. No. 4,864,152 (Pedersen, 1989); U.S. Pat. No. 5,798,572 (Lehoczky, 1998); U.S. Pat. No. 6,508,191 (Spoljaric, 2003). These turbine-oriented (that is, in the context of this specification, axially-oriented arrangements of impeller and generator) inventions, from the dates involved, demonstrate the same longevity and prevalence for such an endeavor, lasting into (and with sustained interest) the present time. Also could be cited to further demonstrate the point are explicitly shore-based inventions falling into this category of surface deployment; but as these applications are sufficiently removed from the fully submersed environment and operation of the present invention, such need not be addressed herein.
All such surface or near-surface-oriented inventions rely on mechanical fluidic activity on the surface, and by definition—if employed on a large scale—could present severe disruption to shipping, surface transportation, fisheries, and aesthetics. Further, such inventions are generally inapplicable for a deep-ocean environment in which constant-flow oceanic currents (as opposed to near-shore, tidal or river-based flows) are fully engaged, being precluded by their design via the greater water depths, more severe wave action, and/or distance from shore. The present invention, by contrast, is designed to overcome these obstacles, and harvest energy from strong current activity well beneath the ocean surface, in a practical and maintainable manner.
Specifically submarine power generation by submerged turbine devices is, however, no new goal, as is demonstrated in U.S. Pat. No. 868,798 (McLaughlin, 1907); U.S. Pat. No. 1,123,491 (Corbin, 1915); U.S. Pat. No. 2,501,696 (Souczek, 1950); U.S. Pat. No. 3,209,156 (Struble, Jr., 1965); U.S. Pat. No. 4,025,220 (Thompson et al., 1977); U.S. Pat. No. 4,163,904 (Skendrovic, 1979); U.S. Pat. No. 4,205,943 (Vauthier, 1980); U.S. Pat. No. 4,258,271 (Chappell et al., 1981); U.S. Pat. No. 4,274,009 (Parker, Sr., 1981); U.S. Pat. No. 4,524,285 (Rauch, 1985); U.S. Pat. No. 4,613,279 (Corren et al., 1986); U.S. Pat. No. 4,720,640 (Anderson et al., 1988); U.S. Pat. No. 4,748,808 (Hill, 1988); U.S. Pat. No. 4,868,408 (Hesh, 1989); U.S. Pat. No. 4,960,363 (Bergstein, 1990); U.S. Pat. No. 6,006,518 (Geary, 1999); U.S. Pat. No. 6,091,161 (Dehlsen et al., 2000); U.S. Pat. No. 6,104,097 (Lehoczky, 2000); U.S. Pat. No. 6,109,863 (Milliken, 2000); U.S. Pat. No. 6,168,373 (Vauthier, 2001); U.S. Pat. No. 6,323,563 (Kallenberg, Jr., 2001); U.S. Pat. No. 6,472,768 (Salls, 2002); U.S. Pat. No. 6,806,586 (Wobben, 2004); U.S. Pat. No. 6,849,963 (Grinsted et al., 2005); and foreign patents JP7259064 (1995, Iwamoto); RU2139972 (1999, Nikolaevich); DE10036314 (2002, Otto, et al.); DE10134509 (2002, Norman, et al.); and AU2002328217 (Barry et al., 2003); see also US Patent Applications 2005-0099012 (Williams, Jr., published 2002); 20050121917 (Kikuchi, published 2005); and 20050132700 (Newman, published 2005). As with the prior citations, the escalation of such patents, in view of their grant dates, underscores the apparent and growing necessity of exploiting truly submarine currents for power generation.
The present invention, however, does not depend upon a specific subsea-capable energy conversion methodology or invention, but is able to accommodate a wide variety of such devices in terms of delivery, electrical connectivity, and maintenance. In contrast with the above inventions, the focus of the present invention is therefore not on a new form of discrete device explicitly designed to convert the flow of water into electrical energy, but rather how to practically deliver such devices—in the evolving state of that art which the numerous citations demonstrate—into the submarine ocean current, in a way that is mechanically and electrically practical, sustainable and maintainable, economically produced, non-invasive to surface-based industry or aesthetics, environmentally-sensitive, and on a scale large enough to make a difference in the energy market.
The category of prior art involving submarine “power plants” follows next, which must be addressed in deeper detail for the attributes of the present invention to be best compared and contrasted. Note that the following comparisons are made from the standpoint of practicality for the invention being deployed in a deeper ocean context, for which the present invention is intended, and even though the compared art may not have been so designed. Indeed, many of the following are explicitly or implicitly designed for shallower installation only. However, for the purposes of demonstrating the novelty of the present invention in regards to greater deployment depths, such comparisons must be made from that perspective of application.
U.S. Pat. No. 3,922,012 (Herz, 1975) employs a barge equipped with vertical-axis “turbines.” This invention, however, involves a complex system of interconnected shafts, gearing, bearings, and so forth, the maintenance involved seemingly limiting its application to a shallower installation—as seems to be confirmed by the frequent usage of the term “tidal.” The invention further appears to be intended for permanent or semi-permanent installation upon the seabed, for no provision is given for freeing it from the ocean floor silt into which it will perhaps sink, or for practically pressurizing (if applied to greater ocean depths) its pontoons. If installed in deeper waters where major ocean currents can be engaged, such a seabed emplacement (with no vertical operational positionability in the water column) would not take advantage of the fact that practical and optimal engagement of said current may occur well above the sea floor. The same can be said of any submarine “power plant” directly deposited on the seabed, in a deeper-water application. The present invention however, while being “barge-like” in appearance and being able to bear a plurality of true turbines, has little or no practical resemblance to the Herz invention. Instead, it is intended for suspended operation in the water column, with vertical and angular means of positioning.
U.S. Pat. No. 4,026,587 (Hultman et al., 1977) represents a power plant based on a single turbine. The device is permanently installed on the seabed and incorporates a pivoting base, underscoring its tidal (as opposed to unidirectional current) application. The assembly is huge enough for diving bells to dock with it, having a hull thick and spacious enough for workers to enter it for maintenance or operational purposes. By contrast, to avoid the inherent matters of human safety in regards to pressure vessels designed for human occupancy, the present invention is unmanned and remotely operable. Further, it is not installed directly on the seabed, and requires no overall mechanical pivot.
U.S. Pat. No. 4,163,905 (Davison, 1979) is similar to the above, involving a pressure vessel into which workers enter, in order to maintain the complex system of endless chain and paddles. Near-surface operation is implicit in the mode of its structural presentation; even so, like Hultman, human safety issues and code requirements in regards to human-occupied pressure vessel design are brought to bear. The present invention, as has been mentioned, avoids such difficulties by virtue of being unmanned (but surface-maintained).
U.S. Pat. No. 4,219,303 (Mouton, Jr. et al., 1980) builds upon the idea of a practical submarine power plant, incorporating an array of tethered turbines being suspended between ocean floor and surface. Mouton's approach for more significant levels of power generation involves, however, the enlargement of the basic turbine, with blades large enough to require annular bearings (that is, without axles). The present invention embraces the same notion of a hydroelectric turbine array. But instead of huge individual turbines, a greater array may be comprised of several submersible platforms as presented herein, each platform bearing a local “array” of comparatively smaller and mechanically simpler energy-conversion devices.
U.S. Pat. No. 4,256,970 (Tomassini, 1981) involves a platform on legs that reach to the seabed. Similarly, U.S. Pat. No. 4,335,319 (Mettersheimer, Jr., 1982) is also leg-supported, and having its prime components (other than impeller) being elevated above the ocean surface. Both are therefore difficult to apply to a deep-water application, as opposed to the present invention which is suspended in the water column, and designed to engage sub-surface currents at greater depths.
U.S. Pat. No. 5,440,176 (Haining, 1995) presents a submarine power plant, with its motive components located on the sea floor. The invention is analogous to that of an “oil platform”: a “rig” with legs resting on the ocean floor, but with the supported superstructure being fully submarine as well; and instead of a pipeline, cables reach to shore. The invention focuses however on turbine devices that move up, down and axially relative to their fixed undersea platform, implying a tidal (and thus shallower water) application. If the invention were set in a deeper ocean environment, wherein the purpose was for the engaging of constant-direction current, the need for these directional mechanisms would be obviated. In comparison, the present invention is designed for unidirectional current flow (or practically so), has no such concrete tie to the ocean floor, is suspended at a selectable operating depth (which will often not be optimal near the seafloor), and is designed explicitly for the surfacing of motive components for maintenance.
U.S. Pat. No. 4,306,157 (Wracsaricht, 1981) presents a practical submarine turbine assembly that transmits power to shore. The invention, however, is comprised of a discrete turbine device: statically installed, inherently near-shore, with no provision for its maintenance being readily apparent. If deployed in quantity in a deep ocean environment, such factors could be seen as problematic. The present invention, however, can deliver turbine devices to greater depths, addresses conveyance issues of power thereby generated, and provides for their periodic surfacing for maintenance.
U.S. Pat. No. 4,383,182 (Bowley, 1983) builds upon the hydrodynamic, twin-impeller design of the (river-installed) invention of U.S. Pat. No. 2,501,696 (Souczek, 1950), but with a different motive approach (hydraulic pumping, the pressurized fluid thereby energizing a generator). Both these inventions involve an airplane-like approach to engage the current; both are hard-tethered to the seabed (or, like Souczek, the riverbed). Both have buoyancy-control implications, which are addressed by U.S. Pat. No. 6,091,161 (Dehlsen et al., 2000). Even so, each of these represent a strictly twin-impeller underwater airplane-like device, whereas the present invention can accommodate a larger quantity, and relies on differing means of positional control.
U.S. Pat. No. 4,850,190 (Pitts, 1989) employs an array of tethered equipment, amongst which are buoyant turbines. A surface ship is required, and no technical explanation for disengaging the turbines for maintenance is evident. The purpose of this free-floating network is the generation of hydrogen. The present invention bears an array of turbines mounted to a fixed and retrievable structure, and is focused upon the generation of electrical power as the primary purpose. That being said, the present invention is, by a different selection of payload equipment, equally amenable to hydrogen production.
U.S. Pat. No. 6,531,788 (Robson, 2003) is a tethered device, with active buoyancy control, and therefore a capability of depth variation. It explicitly consists, however, of an arrangement of a single pair of counter-rotating turbine generators, a “streamlined buoyancy tank” that is “torpedo-shaped,” and “airfoil-shaped hydrofoils.” That is, it is an explicitly twin-generator invention intended for horizontal operation. The Robson invention further claims to be “free of service or replacement for a period of time ranging from about eight to twenty years,” such freedom being “accomplished by eliminating moving parts,” and using corrosion-resistant materials. Indeed, the device “will not be readily accessible for servicing and repair.” Thus, a permanent submerged installation appears to be in view. The invention presented herein, however, can bear many generator units, of various styles, and retrieve them as maintenance schedules require.
Foreign patent W02005028857 (2004, Perry, et al.) is (or may be) hard-tethered to the seabed; but the composite array of paddles-on-chains represents a single power-generating “turbine” apparatus, does not appear to have means of vertical positionability in the water column, and does not provide for interchangeable turbine devices.
Foreign patent application JP2002127988 (2002, Takemoto) presents a horizontal buoyant frame tethered to the ocean floor into which coaxial series of turbines are installed. The present invention though is designed for a variety of energy-conversion devices individually (as opposed to sequentially/coaxially) presented to the ocean current, for improved mechanical advantage.
US Patent Application 20040189010 (Tharp, published 2004) involves a series of specific forms of perpendicular-axis generator devices mounted to cradles anchored on the seabed, in contrast with the present invention which is intended to be suspended at a distance from the seabed, without relying on a particular type of generator design.
It should be noted that, aside from a review of US and foreign patents, the prior art additionally encompasses various undersea electrical generator systems that are of public knowledge, particularly those under investigation in the UK. The systems researched (as part of the investigation into prior art), however, generally involve a hard mechanical connection to the ocean floor (as opposed to variable tethering) or a basis at the ocean surface (via a floating barge-like structure). Such are therefore fixed and limited in operating depth, and are furthermore specifically tidal in design and application. The present invention, by contrast, addresses a unidirectional (or practically so) ocean current, engaged in areas wherein ocean floor depths tend to preclude the aforementioned approaches by virtue of their design.
A final group of prior art for consideration is that of submarine systems that have nothing to do with power generation, but which have relevance in view of the multi-purpose means of submarine delivery afforded by the present invention. U.S. Pat. No. 3,220,372 (Lehmann, 1965) is a submersible barge that directly comes to rest on a base frame installed on the seabed, something not involved in the present invention. A similar purpose and approach can be seen in U.S. Pat. No. 4,860,681 (Svenning, 1989), though in a much more elaborate manner. U.S. Pat. No. 3,293,867 (Dean, 1966) presents a means of reestablishing mechanical contact with an undersea wellhead, and indeed involves a buoyant platform with powered take-up winches. The present invention, however, does not have the ocean floor as its operational destination.
U.S. Pat. No. 3,626,703 (Richburg, 1971) includes an arrangement of buoys and moorings, intended to guide a submarine vehicle in its operations. However, it operates exclusively from a surface ship. U.S. Pat. No. 4,278,362 (Scherrer, 1981) is designed to repeatedly retrieve and re-deploy a submarine device by tethered and buoyant means; it relies, however, on a specialized receptacle on the ocean floor to receive the submergible object, and a seabed position of device operations. U.S. Pat. No. 4,557,697 (Kontar et al., 1985) has similar purposes; but the invention relies entirely on variable buoyancy for depth control.
Numerous other submarine systems and inventions (that do not focus on undersea power generation) might be cited, in that one element or another might be seen to be analogous in a particular aspect of the present invention. But like those examples that are cited, none have the purposes of the present invention for electrical power generation, nor the same approach to achieving the delivery and retrieval of primary equipment involved. Likewise, much more could have been said concerning the discrete devices surveyed that do indeed have submarine current-motivated power generation as their objective. Yet the present invention does not focus on explicit energy-conversion inventions (or pairs of such), but on a practical means of presenting an array of such devices to subsurface ocean currents in the water column, and retrieving the same for maintenance.